In the past, catalytic cathodes for zinc-air cells were generally of catalytic metal powders and more recently of activated carbon with catalytic metal oxides such as MnO.sub.2. For example, Paynter et al., U.S. Pat. No. 3,649,361 issued Mar. 14, 1972, teach such a catalytic cathode comprised of a finely divided activated carbon powder and a catalyst material selected from a class consisting of a mixture of manganese dioxide and a manganese oxide and at least one other base metal catalyst.
Armstrong, U.S. Pat. No. 3,948,684 issued Apr. 6, 1976, teaches a process for preparing a gas permeable hydrophobic electrode structure (i.e., catalytic cathode) wherein a manganese dixoide catalyst is bound to both faces of a grid and a hydrophobic semi-permeable membrane is placed on one side of the coated grid. The manganese dioxide is produced in situ by decomposing an alkaline metal permanganate on an activated carbon substrate.